Skip to main content

Full text of "Text Book Of Mechanical Engineering"

See other formats



3 02                              Appendix II.

.-.   Velocity due to steam =  ^2/H =

+ V 2^H =

+ *

and Total Velocity

which value must be used instead of v on page 98.

s is more rigidly correct for mean total

Also P = 

pressure, though the addition is only slight. Thus, by calculation
a 5-cwt. hammer gives a blow of about 20 tons, half a ton of which
is caused by Ps, the pressure of the steam. (See p. 98.)

P. 124.. Stamping,  It is indeed remarkable how a difficult
forging may be overcome by the use of top and bottom dies, and
although the method ha.s its limits, it may be pushed to very

extreme cases, if we partly forge by hand and partly stamp under
a hammer. The metal should always be roughly forged or
welded to shape, however, before placing in the dies, so as to
dispose the fibre in the best direction for strength. Some seven
.examples are shewn: (i) The single-webbed crank, Fig. 12r,
Reeding no further explaaatiori; (2) the centre for screwing stock,